I just rebooted my trusty Netra T1 with a shiny new 4.99.48 kernel and
thought I'd kick off a userland build. Things seemed to go swimmingly
for a few minutes, then the machine ground to an un-usable state --
userland seems to be mostly non-responsive, though the machine is
pingable, answers a ^T at a tty (well, it seems to be wedged harder
now.. it did for a while after the apparent lockup), and the disk sounds
like progress is being made on the build.
But, I can't get any echo from a tty anymore, and god forbid I should
want to log in ;)
Anyone seeing anything similar? Should I go back to the last-known-good
kernel for a while? ;)
Machine is a Netra T1 200 -- UltraSPARC-IIe @ 500 MHz with 512MB RAM.

So I thought I'd give it one more try, and I saw the same thing happen
this time with a kernel build (thought I'd see if I maybe there was
something else in the latest CVS that would help).

The machine locked up ~ 18:01; it's now 2+ hours later and the disk is
still chugging along. Here's the last thing 'top' on the console said
before the hang:

Unless top's reporting is just way off (it didn't seem to be at the
start), there's a sucking memory leak somewhere -- where'd the other 500
MB of memory go?

DDB's ps/l (as well as backtrace) also shows an interesting fact -- the
active LWP is the system idle loop every time I'd ended up in DDB due to
this hang.

vmstat seems to confirm this is due to some memory-related condition...
stats below are samples every 2 seconds (I'm impatient ;)). This has
happened every time I've started off a more significant build on this
box running 4.99.48 -- be it just a kernel build or an attempt to build
the whole system.